U.S. · IRS letters
IRS LT16 notice explained.
A collection notice about unpaid taxes and/or missing returns.
The LT16 notice means the IRS is trying to collect unpaid taxes and/or its files show missing tax returns. The IRS page says it is essential to take action to avoid possible enforcement, which it says can include seizing assets or wages or filing a notice of federal tax lien. It tells you to read the notice, file any missing returns and pay or arrange to pay. The page prints no number of days; follow your notice.
Compare IRS letters and notices
Result
IRS letters and notices at a glance
| Letter or notice | What the IRS page says it is | Response, as the IRS page states it |
|---|---|---|
| Letter 12C | The IRS needs more information to process your individual income tax return: missing or corrected forms or schedules, verification of income, withholding and credit amounts, or verification of taxpayer identification numbers or Social Security numbers. | Send the information requested within 20 days. Respond even if you disagree, with a clear explanation. Do not file Form 1040-X. |
| Letter 4464C | Verifying your income and income tax withholding on a return. | If you filed a return, no action is needed. Do not call until 60 days after the letter date, and only if you have not received your refund or heard from the IRS by then. |
| Letter 4800C | The IRS is proposing a change to your tax return. | Complete and return the Response Form within 30 days from the date of the letter. If you disagree, reply with supporting documentation. |
| Letter 4883C | The IRS received a Form 1040-series return filed under your SSN or ITIN and needs you to verify your identity and the return to continue processing it; if you didn’t file one, you must let the IRS know. | Call the Taxpayer Protection Program Hotline shown in your letter immediately, with the listed documents on hand. The page prints no number of days. |
| CP5447 series (including 5447C) | A Form 1040-series return was filed under your SSN or ITIN, and the IRS needs you to verify your identity and the return. | Verify your identity and the return. If you can’t verify online, verify by phone, by mail or with the Document Upload Tool as your notice instructs. The page prints no number of days. |
| Letter 5747C | The IRS received a Form 1040-series return under your SSN or ITIN and needs to verify your identity and the return; you may need to visit a Taxpayer Assistance Center. | Act immediately. If you didn’t file, call the Taxpayer Protection Program hotline on your letter. If you did file, call the Taxpayer Assistance Center number on your letter to schedule an in-person appointment. The page prints no number of days. |
| Letter 6419 | Advance Child Tax Credit Reconciliation: the total of 2021 advance CTC payments and the number of qualifying children used to calculate them. | No response is requested. Families who received advance payments must file a 2021 return and compare the payments received with the CTC they can claim. Keep the letter with your tax records. |
| Letter 6475 | Economic Impact Payment (EIP) 3 End of Year: the total third Economic Impact Payment and any plus-up payments received for tax year 2021. | No response is requested. The letter helps determine whether you are eligible to claim the Recovery Rebate Credit on your 2021 return. |
| LT16 notice | The IRS is trying to collect unpaid taxes and/or its files show you are missing tax returns. | Read the notice and follow its instructions. File any missing returns, pay the balance, or pay what you can and set up an installment agreement. The page prints no number of days. |
| Letter 2800C | The IRS believes your employee may have filed an incorrect Form W-4, Employee’s Withholding Certificate. | Begin withholding income tax from the employee’s wages at the rates in the letter, effective 60 days from the date of the letter. Contact details are on the IRS page and the letter. |
| LT11 notice | The IRS hasn’t received your payment for overdue taxes and intends to seize your property or rights to property. You must contact the IRS immediately. | Contact the IRS immediately. Pay the unpaid balance, pay what you can, or request an installment agreement. To appeal the proposed levy, follow the instructions on the letter. The IRS page prints no number of days. |
| LT38 notice | An update on your outstanding balance because some collection notices were suspended during the pandemic and normal operations are resuming. It isn’t an audit. | Read the notice and follow its instructions. File any missing returns and pay the unpaid balance; if you can’t pay in full, see the page’s options. The page prints no number of days. |
| LT39 notice | A written reminder, required by law, about your overdue balance and any missing returns. | Pay the balance due on or before the due date on the notice. File any missing returns. If you’ve already paid, call the number on the notice. |
| Letter 2531 | Information reported on your tax return doesn’t match information reported to the IRS by third parties. The response form named on the page is for business (BMF) income tax returns. | Complete and return response Form 15114 by the date shown on the letter, saying whether you agree or disagree. If you disagree, attach a signed statement explaining each item. |
| Letter 4310C | Someone may have attempted to impersonate you using your name and Social Security number; the IRS says it resolved the issue through processing safeguards and flagged your account. | If you already filed the return for the year on the letter, submit nothing. If you haven’t, file a paper return by mail to the Submission Processing Campus for your state. Follow the letter’s instructions. |
The letter or notice number is printed on the document itself. Use it exactly as printed; the table follows the IRS page for each number. Where a response time is not printed on the IRS page, the table says so and the date on your own letter controls.
What the IRS page says the notice is
The page says that if you received a simple LT16 notice, it’s because the IRS is trying to collect unpaid taxes from you and/or its files show it’s missing tax returns from you. It says enforcement action can include seizing your assets or wages, or filing a notice of federal tax lien, which could affect your credit score and ability to borrow.
What the IRS page asks you to do
Read the notice carefully; the page says following its instructions may stop enforcement action. File missing returns if the notice lists any. Pay the unpaid balance; interest and applicable penalties stop being added once the balance is paid in full. If you can’t pay in full, pay what you can and set up an installment agreement for the rest, for which the page says you must be current on your filings. If you owe less than $50,000, the page says you may be able to use the Online payment agreement application; otherwise call the toll-free number on the notice or mail in an installment agreement request.
Appeal rights
The page says that if the tax is in doubt, you dispute the amount of the tax, or can’t resolve a disagreement with the IRS, you’re entitled to a hearing with the Office of Appeals. It points to Publication 1660, Collection Appeal Rights, and to the toll-free number on your notice. It prints no deadline for requesting one here.
Payments, hardship and relief
The page says payments can take up to 21 days to post and that if you paid in full within the last 21 days you can disregard the LT16. If paying would cause a financial hardship, it says the IRS may report an account as currently not collectible, which doesn’t stop penalties and interest and doesn’t make the debt go away, and it mentions the offer in compromise and the Offer In Compromise Pre-Qualifier Tool. It also says you may qualify for relief from penalties for circumstances beyond your control.
More IRS letter pages
Other pages in this set: Letter 12C, Letter 4464C, Letter 4800C, Letter 4883C, CP5447 series, Letter 5747C, Letter 6419, Letter 6475, Letter 2800C, LT11 notice, LT38 notice, LT39 notice, Letter 2531, Letter 4310C. For the codes on an IRS account transcript, see the IRS transcript codes lookup. For how interest and penalties are worked out on a balance, see the IRS penalty and interest calculator.
Sources
- Understanding your LT16 notice: what the letter or notice is, what to do, and the help and reference items. Read November 2, 2026.
IRS page last reviewed May 5, 2026. This page restates what the IRS page says and adds nothing beyond it: no timelines, outcomes or advice that the IRS page does not state. The IRS can change a letter page at any time; the letter you received controls, including its response date and contact details.
Frequently asked questions
What is an IRS LT16 notice?
The IRS page says it is sent because the IRS is trying to collect unpaid taxes from you and/or its files show it’s missing tax returns from you.
What can happen if I ignore an LT16?
The IRS page says enforcement action can include seizing your assets or wages and filing a notice of federal tax lien, which could affect your credit score and ability to borrow.
What if I already paid after getting an LT16?
The IRS page says payments can take up to 21 days to post, and if you paid your balance in full within the last 21 days, disregard the LT16.
Can I appeal an LT16?
The IRS page says that if the tax is in doubt, you dispute the amount or can’t resolve a disagreement, you’re entitled to a hearing with the Office of Appeals, and points to Publication 1660, Collection Appeal Rights.
What if I already filed a return the LT16 says is missing?
The IRS page says that if it has been over 10 weeks since you sent the return, send a signed copy again, and if a return was incorrectly reported as missing, call the toll-free number on your notice.
Not tax or legal advice
This page summarizes IRS letter and notice pages and is not tax, legal or financial advice. It does not tell you how to respond beyond what the IRS page states. The letter you received controls. A CPA, enrolled agent or tax attorney, or the IRS number printed on your letter, can confirm what applies to you. Everything runs in your browser; nothing you enter is sent anywhere.